Was missing 2 bronze, now they're done and no Orb. Might be a Silver Challenge, but that would be weird considering it was supposed to be really easy to get!
Maybe my savefile is bugged? I don't have that Gaan level as well. In the unlock thread it says that Gaan is "Opened by quest progression in game and getting one of every trophy."
I have all Vicious Dungeons (except Gaan) but I don't event have Gaan Hard level.
Could you post a picture of how my dungeons map should look like? :S